Flexible ceramic material, as a fundamental component of a toolset for the design of multifunctional materials, is very desirable, but a simple and effective preparation strategy is still missing. Herein, a flexible Si 3 N 4 /MnO 2 ceramic membrane was fabricated by facile vacuum filtration progress using hard Si 3 N 4 particles and soft ultralong MnO 2 nanowires as building blocks. The Si 3 N 4 particles were uniformly anchored into the porous flexible membrane, depending on the mechanical entanglement from ultralong MnO 2 nanowires, resulting in the excellent interface stability between them. Thanks to the flexibility of MnO 2 nanowires and interface stability, the as-prepared flexible membrane achieves superior flexibility including bending, folding, and twining. The flexible ceramic membrane can broaden the application range beyond the traditional ceramic use as hard structural materials. Moreover, the design strategy developed herein is applicable to other hard ceramic with similar issues.
Qiang Zhi,Shan Zhao,Baoqiang Hou,Nanlong Zhang,Feng Li,Bo Wang,Jianfeng Yang
Highly porous Si 3 N 4 ceramics with unidirectionally aligned pore channels are gaining significant attention across various fields due to their outstanding functional capabilities. However, achieving high strength in such unidirectional highly porous Si 3 N 4 ceramics remains challenging. Herein, we design and fabricate a novel β-Si 3 N 4 scaffold composed of directionally aligned lamellar walls with a textured microstructure by directionally freeze casting of α-Si 3 N 4 suspensions with fine elongated β-Si 3 N 4 seeds addition, followed by liquid phase sintering. During the sintering, the scaffold exhibited anisotropic shrinkage, and fibrous β-Si 3 N 4 grains were synthesized through epitaxial growth on the seeds preferentially oriented or the nuclei originated from α-Si 3 N 4 powders, resulting in the grains aligned parallel to lamellar walls and bridged the walls. Seed additions of 7 to 15 wt% were beneficial for the optimized distribution of the two types of β-Si 3 N 4 grains, which contributed to the excellent resistance to bucking-induced fracture for the walls. Compared with other unidirectional porous Si 3 N 4 prepared by freeze-casting in the literature, the Si 3 N 4 scaffold exhibited outstanding compressive strength, ranging from 2.8 to 22.0 MPa, as the porosity decreased from 94.4% to 88.0% and the density increased from 175 to 365 mg/cm 3 . The lightweight and strong Si 3 N 4 scaffolds are promising candidates for engineering applications in harsh environments.
危险品化学品经营许可证（带存储）